1. Technical Field
The present invention relates to optical receiver systems and methods of operation and, in particular, to methods and systems for managing the optical power of signals in such receivers.
2. Description of the Related Art
A reconfigurable optical add/drop multiplexer (ROADM) node is an important optical network element that permits flexible adding and dropping of signals on any or all wavelength division multiplexing (WDM) channels at the wavelength layer. A multi-degree ROADM node (MD-ROADM), which can be a ROADM node with 3 degrees or higher, is another optical network element that also provides a cross-connection function of WDM signals among different paths. Although conventional ROADM nodes have a certain degree of flexibility for adding and dropping signals on WDM channels, they do not possess sufficient flexibility to adapt to rapidly growing and increasingly dynamic Internet-based traffic. For example, transponders employed by conventional ROADM nodes typically do not have non-blocking and wavelength transparent access to all dense wavelength division multiplexing (DWDM) network ports. As a result, colorless and directionless (CL&DL) MD-ROADM nodes have been widely studied recently to replace conventional ROADM nodes. In this context, “colorless” can refer to an ROADM node feature by which each transponder can receive and transmit signals on any wavelength employed by the ROADM node system. In turn, “directionless” can refer to an ROADM node feature by which each transponder connected to the node can receive signals originating from any input port and can forward signals to any output port of the ROADM node.